Valence band spectroscopy on lignin

The valence band of lignin and sputtered lignin was studied by X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS) and metastable induced electron spectroscopy (MIES). The corresponding spectra were compared with those from fingerprint molecules, representing the various chemical groups of lignin. The results of this analysis show that valence band spectroscopy, in particular a combination of XPS, UPS and MIES, allows an identification of hydroxyl, methoxy and phenyl groups at the lignin surface.